ATF Fluid and engine oil



I got a small amount of engine oil in with my transmission fluid.

Can I drive the car, will it be ok?

Automatic transmission



Transmission fluid is carefully formulated to provide the right amount of lubrication as well as enough internal friciton to make the clutches work. Adding engine oil will affect those qualities and make it slip or malfuntion.

I would go to a good independent shop and have the fluid drained and filter changed , about $100 or so for most cars.


small=? 1 drop? 1 cup? 1 quart?


about 1/4 cup


Get it out.


Its NOT going to hurt it. I have run automatics with a lot more than that in them. I build automatics and run them on anything from 100% motor oil to pure hydraulic fluid just to see what they would do and how long it would take me to blow it up. My wife tells me I’m destructive and have too much time on my hands…LOL Seriously though, unless you really want to, you dont need to drain your trans.



transman, can you share with us what happens when you put motor oil in an automatic transmission, or hydraulic fluid? That would be interesting.


Sure can. I did this a couple of years back. Spent about 6 months or so when the shop got slow. Used both front and rear wheel drive transmissions, electronic and hydraulic, 10-30 dyno oil and fully synthetic motor oil. My brother had a 5 gallon bucket of hydraulic fluid in his shop one day that he used for his wrecker so I decided to try that too. I even tried power steering fluid once. It didnt work as well but I didnt go much farther with that yet. I might try it again sometime If I find myself getting a little bored. Motor oil in a 4L60E worked better than I thought. Normal driving it shifted out pretty good. TCC lockup was the big problem with both the motor oil and the hydraulic fluid. TCC chatter was a BIG issue. All line pressure specs were normal, pressure control solenoids responded normally when adjusted by scanner. Punching it off the line with motor oil showed slippage. Scanner showed TCC slip RPM more than double the acceptable under light acceleration. (I dont remember the exact numbers though, I wrote them down). The hydraulic fluid stayed surprisingly clean and all clutches still looked new after disassembly. I did lock out the TCC and drove the vehicle approx 100 miles before disassembling and inspecting. I just couldnt get those TCC’s right. Give me some more time and I might be able to. Havnt played with them much more lately. I spend most all of my off time with my 3 year old daughter, she keeps me busy.

Thats basicly what I did in a nutshell. I played with things like clutch pack clearances, kevlar-v-stock bands and clutches, tweaking valve bodies, drilling spacer plates trying to get better shifts with the different oils. About the only thing I didnt do, and I regret it now is take pictures and video what I did.



Haha. Amazing. For some reason that reminds me of what they used to do in a muffler shop I once worked in part time. The one hydraulic lift was leaking fluid into the ground. So they put vegetable oil in it instead of hydraulic fluid since vegetable oil wasn’t “hazardous waste”.